The third stop of the Diamond League will see some of the world's best distance runners clash at America's premier Prefontaine Classic in the 5,000m race providing a preview of what to expect at the London World Championships final.

Kenya's world cross country champion Geoffrey Kamworor and Caleb Mwangangi Ndiku are some of the top runners who will take their war against Britain's Mo Farah to Eugene, Oregon on May 26-27.

The challenge includes half of the field having an Olympic or World Championships medal. There is plenty of talent on show beginning with every Olympic medallist from Rio, reports Xinhua news agency.

Kamworor, 24, has the most major gold medals of anyone in the field except Farah. In March, the Kenyan won his second world cross country crown. Last year he won his second world Half-Marathon title.

On the track, he has run personal best time in all three appearances at the Pre Classic, including last year's runner-up finish at 12:59:98 minutes.

"I see this as another chance to prove how fit I am. It might not be a contest to beat Farah, because this is my first race of the season in the track. But I believe it will indicate where I rank and would prefer to improve on that after," said Kamworor, Friday in Nairobi.

Another Kenyan, Ndiku, 24, earned the silver medal in the 2015 World Championships in Beijing.

The Kenyan won the Pre Classic 5k in 2014, the year he also won the Diamond League title.

In his first Pre Classic appearance in 2011, Ndiku joined the sub-3:50 club with a 3:49.77 in the Bowerman Mile. It is still his fastest mile ever.

"I have more focus on the 5,000m now and this will be good field for me to test how we rank. But I always take up a challenge with intent to win irrespective of the rivalry involved," he said.

Indeed running against Farah, who is 34 is a big test and the Briton now has nine major gold medals -- four in the Olympics and five in the World Championships, and eight from an uncanny collection of double 5k/10k wins at the last two Olympics and last two World Championships.

He is aiming for another double at this summer's London Worlds. Farah's success at the Pre Classic mirrors his other global success.

He has racked up four Pre Classic victories -- the still-standing 5k meet record of 12:56.98 in 2012, plus three wins in the 10k (the three fastest of his career).

But there will be more challenges from Kenyan-turned American Paul Chelimo, who was the surprise silver medallist in Rio.

Having earned U. S. eligibility just a year earlier, he made history with the first Olympic 5k medal by an American since Bob Schul won the 1964 Tokyo Olympics.

Chelimo was the only runner challenging Farah on the homestretch in Rio, and his 13:03.90 was a new best by over 15 seconds.